Bug report

Required Info:

• Operating System: Ubuntu 22.04
• Installation type: Binaries (ros:humble docker image)
• Version or commit hash: latest as of now (9bf1a5b14fd9)
• DDS implementation: Fast DDS (rmw_fastrtps)
• Client library (if applicable): I believe ros2 topic echo leverages rclpy

Steps to reproduce issue

FROM ros:humble

SHELL ["/bin/bash", "-c"]

WORKDIR /root/demos/src
RUN git clone https://github.com/ros2/demos.git

WORKDIR /root/demos/
RUN source /opt/ros/humble/setup.bash && \
    colcon build --event-handlers=console_direct+ --packages-select topic_statistics_demo

RUN echo 'source /opt/ros/humble/setup.bash' >> ~/.bashrc
RUN echo 'source /root/demos/install/setup.bash' >> ~/.bashrc

1. Build the image with:

   docker build -f Dockerfile -t ros2_cli_statistics_bug .

2. Run the image:

   docker run -it --rm ros2_cli_statistics_bug:latest /bin/bash

3. From within the container, run the display_topic_statistics application from the topic_statistics_demo package. This will create a publisher and a subscriber on the /topic_statistics_chatter topic. The subscriber will publish statistics onto the /statistics every second. The demo also creates a subscriber to the /statistics topic and displays the statistics on the screen, all of which works alright.

   ros2 run topic_statistics_demo display_topic_statistics string

4. Open another shell on the same container with:

   docker exec -it <container-id> /bin/bash

5. Try to echo the /statistics topic from within the new shell. At this point, ros2 topic list shows all the topics correctly, and echoing /topic_statistics_chatter is working, but echoing /statistics does not work.

   source ~/.bashrc
   ros2 topic list # <------------------------------ OK
   ros2 topic echo /topic_statistics_chatter # <---- OK
   ros2 topic echo /statistics # <------------------ NOK

Expected behavior

I would expect ros2 topic echo /statistics to work, as I have not found documentation stating otherwise, please correct me if I'm wrong.

Actual behavior

ros2 topic echo /statistics fails with the following error:

Unable to convert call argument to Python object (compile in debug mode for details)